CB formation is dependent on coilin interaction with snRNPs. (A) Hela^coilinKO and parental HeLa cells transfected with EGFP-coilin^WT or indicated coilin variants and detected by EGFP fluorescence (left panel, green in merge image). snRNPs were immunolabeled by Y12 antibody (middle panel; magenta in merge image). Insets show CBs marked by arrows magnified three times. Scale bars represent 5 µm for whole cell images, 1 µm for insets. (B) Immunoprecipitation of EGFP-coilin followed by western blotting using markers of snRNPs: SmB/B' (top panel) and SART3 (U4/U6 marker), PRPF6 (U5 marker), and SNRNPB2 (U2 marker) (bottom panel). (C) Immunoprecipitation of EGFP-coilin followed isolation of RNA. RNA was resolved by PAGE/UREA gels and silver stained. Positions of snRNAs and rRNAs are indicated. (D) Immunoprecipitation of EGFP-coilin WT and EGFP-tagged mutants followed by western blotting using anti-coilin antibodies. Positions of EGFP-coilin and endogenous coilin are indicated. Source data are available for this figure: SourceData F6.